Physical activity and exercise recommendations for people receiving dialysis: A scoping review

Introduction Remaining physically active is important to patients undertaking dialysis, however, clinical recommendations regarding exercise type, timing, intensity, and safety precautions vary. The purpose of this scoping review was to analyse and summarise recommendations for physical activity and exercise for people undertaking dialysis and identify areas that require further research or clarification. Materials and methods A scoping review of literature from five bibliographic databases (Medline, Scopus, Web of Science, CINAHL, and SPORTDiscus) was conducted. Eligible articles included consensus guidelines, position statements, reviews, or clinical practice guidelines that included specific physical activity and exercise recommendations for people undertaking dialysis. Key search terms included "kidney disease" OR "kidney failure" OR "chronic kidney disease" OR "end stage kidney disease" AND guideline* OR consensus OR "position statement" OR prescription OR statement AND exercise OR "physical activity". Hand searching for relevant articles in all first twenty quartile 1 journals listed on SCImago under ‘medicine—nephrology’ and ‘physical therapy, sports therapy and rehabilitation’ using the terms ‘exercise and dialysis’ was undertaken. Finally, home pages of key societies and professional organisations in the field of sports medicine and nephrology were searched. Results The systematic search strategy identified 19 articles met the inclusion criteria. Two were specific to pediatric dialysis and three to peritoneal dialysis. Whilst many publications provided recommendations on aerobic exercise, progressive resistance training and flexibility, few provided explicit guidance. Recommendations for the intensity, duration and frequency of aerobic and resistance training varied. Discrepancies or gaps in guidance about precautions, contraindications, termination criteria, progression, and access site precautions were also apparent. Conclusion Future guidelines should include specific guidance regarding physical activity, safety precautions, and timing and intensity of exercise for individuals who undertake dialysis. Collaborative multidisciplinary guideline development and appropriate exercise counselling may lead to increased participation in physical activity and exercise and facilitate better patient outcomes.


Introduction
Globally, over seven million people with kidney failure require kidney replacement therapy to maintain life [1]. The most common treatment option for kidney failure is dialysis, with its incidence increasing by 43% since 1990 [2]. In the dialysis population, the lack of physical activity and exercise is associated with poorer quality of life [3], lower physical functioning [4], greater bodily pain [5], increased hospitalisation, and overall poorer survival [5].
Remaining physically active is important to patients undertaking dialysis [6][7][8][9]. Exercise also produces many benefits including improved physical function [3], muscle mass and strength [10]. However, there are numerous barriers to undertaking regular physical activity and exercise. These may be physiological [11], physical [12], psychological, practical [13], as well as structural (such as family support or lack of access to exercise professionals or programs [13,14]). Unfortunately, access to exercise professionals and maintaining the sustainability of structured dialysis exercise programs has been an ongoing challenge for dialysis centers [14]. Dialysis clinicians who aim to support patient physical activity are restricted due to variation and limited guideline recommendations [15].
We sought to undertake a scoping review of the literature regarding guidance for physical activity and exercise for people with kidney failure undertaking dialysis. The specific objectives of this review were to: 1. Analyse and summarise recommendations for physical activity and exercise for people undertaking dialysis.
2. Identify areas that require further research or clarification.

Rationale
Scoping reviews are intended to explore the sources and types of evidence available, and systematically characterise the existing literature on a broad scale. We followed the five stages of a scoping review outlined by previous authors [16,17]: (i) identifying the research questions; (ii) identifying relevant literature; (iii) selecting evidence; (iv) collating evidence; and (v) synthesising evidence. This scoping review is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Scoping Review guidelines [18]. The protocol was published on the OpenScience Framework on 11 September 2020 (Registered form osf.io/g6x8b, Registration DOI: 10.17605/OSF.IO/TNRS5).

Eligibility criteria
Articles considered eligible for inclusion were consensus guidelines, position statements, reviews, or clinical practice guidelines that included specific physical activity and exercise recommendations for people undertaking dialysis. No age restriction was applied, thus documents for both adults and children were eligible for inclusion. Database searches were restricted to English only. However, documents in the grey literature were excluded only if they were unable to be translated by members of the research team. Details of eligibility criteria are included in Table 1.

Search strategies
Comprehensive searching of five bibliographic databases (Medline, Scopus, Web of Science, CINAHL and SPORTDiscus) was undertaken on September 3 rd , 2020 with weekly literature surveillance alerts received until 26 April 2021. All database searches included articles from database inception to search date. The search strategy was informed by similar work in the field of diabetes [19] and guidance from research librarians to refine the search strategy. The key search terms entered included "kidney disease" OR "kidney failure" OR "chronic kidney disease" OR "end stage kidney disease" AND guideline � OR consensus OR "position statement" OR prescription OR statement AND exercise OR "physical activity". Records from these searches were retrieved and downloaded into Endnote (Thomson Reuters; Version X9, 2018). All citations were then uploaded to the Sys.Rev.com open access document review platform (https://sysrev.com/) to facilitate duplicate screening of abstracts by the research team. One reviewer (KL) examined the full text of all citations. Two reviewers (IG and CL) each reviewed 50% of citations. Disagreements were resolved by discussion amongst the reviewers. For studies that passed initial screening, full text articles were retrieved and reviewed by three members of the team to determine inclusion (KL, IG, CL). Grey literature searching involved four search strategies: First, the database CINAHL was specifically utilised to capture grey literature. Secondly, the home page search function of the first twenty quartile 1 journals listed on SCImago under 'medicine-nephrology' and 'physical therapy, sports therapy and rehabilitation' were searched using the terms 'exercise and dialysis'. A request for documentation was placed to all members of the Global Renal Exercise Network (GREX) on 15 September 2020. Finally, home pages of key societies and professional organisations in the field of sports medicine and nephrology were searched until 26 April

Data extraction
One reviewer (KL) independently extracted information from the eligible articles for data synthesis. A second reviewer (IG) checked the accuracy of data extracted from eligible articles. Extracted data included: organisation name or author; type of exercise recommended; mode of exercise; duration; intensity; frequency; safety considerations or additional commentary specific to people undertaking dialysis. In order to analyse recommendations for physical activity and exercise, the following definitions were used: Physical activity refers to bodily movement of skeletal muscles in any manner that results in energy expenditure [20]. Exercise is planned, structured, repetitive body movement intended to produce a health benefit or improve fitness [21].

Results
The systematic search strategy identified 1451 records from database searches and an additional 24 records from the grey literature. After exclusion of duplicates and application of the screening criteria, 19 publications were eligible for inclusion in the review (Fig 1).

Characteristics of selected studies
Eight publications (42%) were obtained from the grey literature [22][23][24][25][26][27][28][29]. Thirteen publications were published on behalf of professional associations or foundations (The American College of Sports Medicine [ACSM] [30], Exercise and Sports Science Australia [31]; European Federation of Sports Medicine Association [27]; the Italian Society of Nephrology [32]; the United Kingdom Renal Association [33]; Chilean Society of Nephrology [28,29]; Amicus Renis Foundation on behalf of the Polish Society of Nephrology [24,25]; the Renal Foundation of Inigo Alvarez de Toledo [23]; Spanish Society of Nephrology [22]; the Kidney Disease Outcomes Quality Initiative [34] and the Life Options Rehabilitation Advisory Council [26]). Two publications were specific recommendations for pediatric dialysis populations [35,36]. Three publications were specific to adults undertaking peritoneal dialysis (PD) [24,28,37]. Six publications were specific to hemodialysis [22,23,26,29,32,33] and six were applicable to both types of dialysis [25,26,28,31,38,39]. Four did not specify the type of dialysis. Fourteen of the 19 publications were published in the last decade. Table 2 summarises the recommendations obtained regarding physical activity. A more detailed summary of recommendations obtained is contained in S2 Table. No publication provided a definition of physical activity nor detail on the type of activities considered as physical activity. Few publications also recommended physical activity explicitly. Advice about physical activity ranged from brief advice such as 'perform physical activity' [28,29] to more explicit information such as 'undertake recreational activity that will contribute to the improvement of cardiovascular and respiratory efficiency' [24,25]. Recommendations for timing and duration of physical activity were contained in only two publications. One publication provided advice for physical activity based on the level of deconditioning, and commenced at 30-60 minutes per day of walking for those who are highly deconditioned or do not exercise [39]. A second publication recommended 30 minutes or more of continuous physical activity 5 days per week [30].

Recommendations regarding aerobic exercise
The majority of publications recommended patients undertake aerobic exercise, and S3 Table highlights that ten of the 19 publications made a specific recommendation to include aerobic exercise for people undertaking dialysis [22, 28-33, 35, 36, 39]. Specific examples of the type and mode of aerobic exercise commonly recommended were walking, running, swimming, and cycling (Table 2). No consensus existed between publications about the recommended duration of aerobic exercise, and recommendations varied from 20-60 minutes per day [24-27, 30, 35, 36] to 15-45 minutes per hemodialysis session [23,31] to 180 minutes per week [31].  Table 2. Summary of recommendations about physical activity and exercise obtained from papers retrieved in scoping review.
Recommendations regarding the timing, duration, and intensity of resistance exercises were variable. The most frequently reported number of repetitions was one set of 10-15 repetitions in the range of 60-75% of 1 repetition maximum (RM) ( Table 2) [23-26, 30, 31, 35, 36, 39]. Several other publications recommended a lower number of repetitions (5-10 repetitions [24,25,27,37]) (S3 Table). The rationale for the reduced number of repetitions was highly variable. One publication indicated a lower number of repetitions (e.g. 1-2 sets of 6-10 repetitions) for low functioning individuals, and for high functioning individuals 2-3 sets of 12-15 repetitions were recommended [37]; however, they did not provide detail on intensity level [37]. One publication provided specific details on intensity on dialysis (1 set to fatigue or 12-15 repetitions) and non-dialysis days (1 set to fatigue or 10-15 repetitions) as well as intradialytic intensity (1 set to fatigue or 12-15 repetitions) [31]. One publication provided detail on intensity but not number of repetitions or sets [34]. Another provided details on number of repetitions and sets but not intensity [23]. Resistance exercises at home were also recommended 5-10 repetitions three times per week at a heart rate intensity that was prescribed by a health professional [24,25].

Recommendations regarding flexibility
Very few publications provided detail or recommendations regarding the inclusion or suitability of flexibility exercises. Of the eight publications that included detail on flexibility, recommendations ranged from arm stretching for those who were wheelchair bound [22] to trunk twists, lateral bends and standing elbow to knee for intermediate and high functioning patients [37]. Five publications recommended flexibility exercises, but no detail or examples were provided [26,27,31,38,39] (S3 Table). One publication specifically recommended balance and flexibility exercises for those at high risk of falls but no additional detail was provided [31]. The most detailed recommendations on flexibility were reported in the ACSM guidelines [30], which provided advice on duration and type of flexibility exercises (60 seconds per joint for static stretches and 3-6 second contraction followed by 10-30 seconds of contraction at 20-75% of maximum voluntary contraction). Ten minutes was described as an appropriate duration for flexibility exercises [30,39] (Table 2).

Recommendations regarding progression of exercise
Details regarding progression of exercise were scarce. A summary of these recommndations is shown in Table 2 with additional detail in S3 Table. Eight publications recommended the progression of aerobic exercise be commenced in a graduated manner [23-26, 30, 33, 34, 38], with one recommending progression be based on individual tolerance but guided by a qualified exercise professional [30]. One publication recommended no aerobic exercise in the first two weeks of an exercise program and to focus on strength training [23]. The majority of publications made no recommendations regarding progression [22, 27-29, 31, 32, 35-37, 39, 40].
Electrolyte, fluid, and dialysis-related contraindications were also reported [25,30,31,33,35,38]. Abnormal electrolyte levels were an indicator to defer exercise [30,31,35,38], with hypo and hyperkalemia considered a contraindication criteria [31,38]. In addition, one publication specified a temporary cessation of exercise if repeated hyperkalemia >6 mmol/L [38]. Significant peripheral edema was also reported as a contraindication [31,33]. Those with an inter-dialytic weight gain of >4 kg was suggested by one publication as a preclusion from intra-dialytic exercise [31]. Hemodynamic stability during dialysis treatment was also considered important, and any patients considered unstable during dialysis were unsuitable for intradialytic exercise (IDE) [31]. For those undertaking PD, recommendations to defer exercise included peritonitis, catheter related infection and a non-functioning catheter [24].

Precautions for dialysis patients
A high degree of variance existed regarding methods to monitor the intensity of exercising dialysis patients (S4 Table). The Borg RPE scale was recommended to monitor intensity, instead of heart rate [30,35,36,39] with one publication providing the justification that RPE should be used over heart rate in patients on beta blockers due to a reduced maximal and submaximal exercise capacity [39]. It was noted that heart rate was not a reliable indicator to monitor exercise intensity in patients on hemodialysis [26,30,36]. The use of telemetry [25,31] was recommended, with one recommending the use of telemetry in all home exercising patients [25], and the other recommending extensive monitoring in those prone to hypo/ hyperkalemia [31]. One publication recommended the use of RPE, however the exercise prescription was based on heart rate [38]. Another publication recommended monitoring both heart rate and RPE throughout intradialytic exercise sessions [33].
No precautions regarding exercise in heat or humidity for interdialytic exercise were identified. Advice to warm up and cool down was provided, but this varied in the level of detail. Limited guidance on warm up and cool down was found other than to encourage the practice [35,36,38], while others recommended 3-4 minutes [26]; 5 minutes [33,37]; 4-6 minutes [23]; or 5-10 minutes [24,25].
Exercise termination criteria was addressed by most publications. These are summarised in Table 2 and additional detail in S4 Table. The most commonly cited reasons to stop exercise included shortness of breath [24,30,33,39], angina [24,30,33,39], dizziness/lightheadedness [24,30,33,39], joint/muscle pain, nausea/vomiting, and discoloration of the face [24,33]. If these signs or symptoms were encountered reducing exercise intensity [38] rather than termination of exercise was recommended. Concerns were expressed regarding hypotensive episodes with post dialysis exercise [30], late IDE [35,36], exercising on vasodilators [39], and exercising in hot or humid environments [39]. Only one publication included a significant drop in blood pressure as a termination criteria [30]. ACSM [30] specified a drop in SBP >10 mmHg with an increased workload and other signs of ischemia warranted the termination of exercise. Unlike most other publications, ACSM provided an extensive list of termination criteria including general and clinical criteria [30].

Specific precautions for hemodialysis patients
For hemodialysis patients performing IDE, exercise was recommended within the first 2 hours of dialysis [30-32, 35, 36], suggesting this reduced risk of hypotension [35,36], contrary to another paper which suggested late IDE could mitigate hypotension in certain individuals [30]. The ACSM advised avoiding participation immediately following hemodialysis treatment due to the increased risk of hypotension [30]. Exercise on non-dialysis days was recommended [25, 26, 30-33, 35, 36], and or avoiding post dialysis exercise [26,30].

Specific precautions for peritoneal dialysis patients
For those receiving PD treatment, caution was advised with exercises that increased intraabdominal pressure [32,38]; however, one reported that even though activities such as straining and weightlifting may increase intra-abdominal pressure, this effect may be of little clinical relevance [37] (S3 Table). Positions to avoid included extensive twisting of the torso, spinal flexion, pulling legs or knees towards the abdomen, abdominal static strength, lying prone or on the side without support [38], strong isometric resistance exercises [32], and intense and long contractions of the abdominal muscles [24]. One recommendation included monitoring the catheter site specifically for increased pressure with upright cycling [22]. Focus on maintaining a steady breathing pattern and avoiding the Valsalva maneuver was also recommended [24,25,38]. Disparities existed regarding fluid volume in the peritoneal cavity prior to exercise ( Table 2). To reduce discomfort, exercising with an empty peritoneal cavity was recommended [30,31]; or partially filled cavity [26,38,39]; and one indicated either empty or partially filled would reduce diaphragmatic discomfort [26]. Maintaining enough fluid 'to allow for floating of the catheter' may mitigate discomfort [39]. Paediatric recommendations included starting with fluid in the cavity and exercising empty if not tolerated well [35,36]. No definition of 'partial fluid' nor intolerance was provided. One publication recommended patients exercise with a full cavity (up to 2L) and suggested that only patients with a history of leaks, hernias, or hypotension exercise with an empty cavity [24].

Access site precautions for patients
Access site precautions were reported in many publications [22,25,[30][31][32][35][36][37][38][39] and are summarised in Table 2. Additional details are shown in S4 Table. For hemodialysis patients using an AVF as the access site, recommendations to avoid exercising the AVF arm during dialysis treatment were offered [30,31,39]. In contrast, four publications stated that the AVF arm was permitted to exercise [30,35,36,39]; however, no guidance on how much weight could be held by the AVF arm was included. Three publications specified that weight could not be directly placed onto the AVF [30,35,36], while one reported on the need for a newly created AVF to heal prior to exercise [39]. Regarding AVF arm positioning, only one publication advised against maintaining the arm above the head for prolonged duration but no timeframe was specified [38]. While many publications reported caution was required at the dialysis access site, many were found to be lacking in detail and vague such as 'not over-exerting the fistula arm' [22, 25, 28, 29, 32-34, 37, 40].

Access site precautions for peritoneal dialysis patients
Recommendations regarding swimming/water safety for patients receiving PD are summarised in Table 2 [22,24,35,37]. Although some publications advised dressing the access site if swimming [22,37], some disparities among these recommendations were evident (S4 Table). This included recommendations to clean the access site and change the dressing immediately after swimming [26,37], dress the access site if swimming [26,35], and securing the catheter with an additional stoma bag for water sports [24]. Two publications included advice against swimming in bodies of water with high level of 'germs' such as lakes and ponds [22,26], and one specifically recommended swimming in chlorinated or seawater instead [26]. Table 3 provides a condensed overview of the guidance found in the publications retrieved and a rating of the quality of evidence and the strength of recommendations contained within these publications. Fifteen publications provided opinion level guidance, while four produced guidance produced by a systematic review of the evidence. # GRADE criteria 1 was used to rate the quality of evidence. Level 1 is a strong recommendation; level 2 a weak recommendation; an A rating suggests high confidence that the true effect is similar to the estimated effect; a B rating suggests moderate confidence in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different, a C rating indicates low confidence and the effect might be markedly different from the estimated effect, and a D suggests very little confidence in the effect estimate. The true effect is likely to be substantially different from the estimate of effect. OPINION statements may be based on expert judgement with or without evidence reviews and are intended to provide guidance to clinicians if the evidence base was low quality or insufficient in size to write a graded recommendation.

Discussion
Few health professionals would dispute that physical activity and exercise provide physical, psychological, and social benefits for people receiving dialysis. This scoping review sought to synthesise current recommendations and identify areas that require further research or clarification. From the 19 publications retrieved, we were able to identify that there is no shortage of guidance on physical activity and exercise for patients who undertake dialysis. While there are some important variations in the level of detail, recommendations on aerobic exercise, progressive resistance training and flexibility were present in many publications. Several publications also provided detail on dialysis-specific topics such as protection of the AVF and exercise in those undertaking PD. New guidance released after the completion of the scoping review is now available for PD [41]. This is an important step forward for health professionals who wish to provide truly patient centred care and help dialysis patients achieve optimal life participation-outcomes indentified by patients as critically important to them [42,43]. Importantly, the scoping review identified major inconsistencies between the available guidance, likely reflecting the low quality evidence base and dated nature of some publications. Inconsistencies were noted in exercise definitions as well as the advice on the frequency (sessions and minutes per week), intensity (assessment of, repetitions), type (aerobic, resistance, flexibility), timing (dialysis vs non-dialysis day; pre/intra/post-dialysis), progression (rate of increasing aerobic activity or weights over time), and safety aspects (medical clearance, contraindications, precautions) of exercise. Dialysis-specific advice also varied, including the presence of recommended volume of peritoneal dialysate during exercise, as well as recommendations regarding swimming and the impact of exercise on intra-abdominal pressure. Overall, the heterogeneity and discrepancies between the published guidance poses challenges for health professionals who wish to provide specific advice about physical activity and exercise to people undertaking dialysis.
The scoping review identified a scarcity of specific guidance about assessment of baseline fitness levels, suitability of exercise in the context of medical co-morbidities, and dialysis-specific exercise precautions (e.g. in patients prone to significant volume or electrolyte shifts, exercise considerations for those with an AVF). Future guidance should address these aspects so that health professionals can encourage appropriate participation in physical activity and exercise.
The terms 'physical activity' and 'exercise' were often used incorrectly and interchangeably across the publications. Though both are important, recommendations for physical activity and exercise should be distinctly different. Very few publications in this scoping review defined or provided specific details on the potential value of physical activity for dialysis patients. This is a missed opportunity to encourage the provision of advice. Physical activity is positively correlated with improvements in mental health, sleep quality and physical functioning scores and negatively correlated with overall mortality risk in people with kidney disease, [5,44,45]. A recent prospective observational study of hemodialysis patients reported an average of 3688 steps per day, with patients over 80 years recording only 1232 steps per day compared to younger patients with 4529 steps per day [46]. Without specific guidance and dialysis specific resource materials, the recommendations to achieve at least 150-300 minutes per week of moderate aerobic physical activity [21] are more difficult.
Other discrepancies with terminology were identified and related to descriptions of exercise intensity. Discrepancies such as this are not unique to nephrology, and position statements to standardise terminology used in exercise recommendations do exist [47]. Unfortunately, variations in definitions of exercise intensity among the dialysis population are not benign and may contribute to inaccurate and ineffective exercise prescription, and potentially cause patient harm. For example, almost three quarters of publications in this review recommended 'moderate intensity' exercise. However descriptions of 'moderate intensity exercise' using the rating of Borg RPE ranged from 10-12 [23] / 11-13 [30,31,35,36] / 12-13 [30] / 12-16 [26]/ or 11-16 [24, 25, 39]. These variations may be associated with the use of unauthorized 'adapted' versions of the original scale. The use of versions of the Borg RPE scale that differ from the original definitions [48] are not recommended. This is because deviations from the original scale are not consistent with the original psychological framework [49], and are associated with inconsistencies in achievement of desired exercise intensity [50].
This scoping review has also identified gaps in current guidelines regarding warm up and cool down for patients receiving dialysis. These elements are distinct components of an exercise training session that appear to be poorly described or not described at all. Given the greater risk of cardiovascular and musculoskeletal complications in the dialysis population [51], the need for guidance in this regard is important. In a healthy population, warm up serves to increase body temperature [52], improve muscle blood flow through vasodilation [53], increase nerve conduction [52], and reduce joint stiffness [52,54]. The preparatory warm up phase may also reduce the likeliness of inducing cardiac ischemia from sudden effort [55,56]. Immediately after exercise a recovery period occurs, which physiologically differs greatly from a warm-up or exercise training. Although the mechanisms of post exercise hypotension in a healthy individual varies between resistance and aerobic exercise [57,58], the recovery period can be considered a 'vulnerable' phase where adequate precautions should be taken [59].
Given the high prevalence of cardiovascular disease in dialysis patients [60], the cardiac physiology of dialysis patients should also be explicitly considered in all future recommendations. Abrupt termination of exercise in patients with coronary heart disease results in a decrease in venous return, decrease in cardiac output, and a reduction in blood pressure [61]. Post exercise hypotension has also been documented in those in the general population with hypertension [62][63][64]. Additionally, those on calcium channel blockers, alpha blockers, and vasodilators may be particularly vulnerable to hypotension immediately following exercise [62,65]. Cool downs, in the form of active recovery, immediately following exercise training can prevent post exercise hypotension [57,62] and syncope [57]. Improving venous return and cardiac preload, via skeletal muscle contractions [57,62], may prevent blood pooling in lower extremities [66]. It would appear reasonable to suggest that dialysis patients should perform an active cool down following exercise. Interestingly, the publications in this review deemed hypotension as an exercise precaution in dialysis patients, however recommendations for adequate cool downs were sparse. Given the lack of dialysis specific guidance for multimorbid patients, it would be reasonable to adopt guidance from organizations such as the ACSM whereby those with cardiovascular, pulmonary, and musculoskeletal comorbidities, are advised to warm up and cool down at a light intensity for 5-10 minutes. Patients suitable for an extended period up to 15 minutes, but not exceeding [19], includes those with heart rate delays with cardiovascular disease. Educating patients about the physiological rationale for warm up and cool down periods is also recommended.
There are several limitations to this review including the restriction of relevant articles to the English, Spanish, and Polish languages only. Documents in the grey literature may also have been missed despite a systematic search strategy. Several guidelines and articles included are also more than a decade old [26,29,34,38] and may not reflect recent advancements in the field of exercise in kidney disease. Strengths of this work include the broad systematic nature of the search strategy utilising the major databases and supplementary search techniques thereby allowing a broad overview of the topic.

Future directions
As a result of this scoping review, we propose several suggestions for future works that are summarised in Table 4. Firstly, specific guidance regarding physical activity should be constructed for people undertaking dialysis given the low physical fitness base. Secondly, guidelines for exercise should contain standardised reporting that includes details of the timing, duration, intensity (e.g. standardised RPE scores and 1-RM measures) frequency and progression of exercise. Specific aspects regarding safety and assessment of appropriateness to exercise should also be included, with explicit instructions on use of the AVF arm, and for people undertaking PD, advice regarding exercise with dialysate in the abdomen. A proposed checklist for authors who intend to publish guidelines for physical activity and exercise in people undertaking dialysis is provided in Table 5. This checklist can be used to improve clarity and standardise recommendations regarding details we have identified to be lacking or vague in the exercise prescription including exercise intensity; inclusion of specific information for patients with cardiorespiratory comorbidities, and details regarding warm up and cool down. The third recommendation that arises from this review is a suggestion for the development of a central clearinghouse for dialysis related exercise information. Given the challenges encountered locating relevant guidance documents for this review, organisations such as the Global Renal Exercise Network [67] could host relevant guidance and resources on their website and/ or link health professionals to relevant documents. This may facilitate the dissemination and wider implementation of advice to people undertaking dialysis.
Recommendations for future research that arise from this review include the suggestion to test an adaption of the Borg scale in plain language for the dialysis population where cognitive impairment and low health literacy are highly prevalent [68,69]. Research exploring staffing of exercise professionals among the multidisciplinary team working in dialysis centres would also be beneficial. Other recommendations that arise from this review include the need for future guidance on physical activity and exercise be directed towards patient-centred and patient important outcomes.

Conclusions
Regular physical activity and exercise are beneficial for people receiving dialysis. While recommendations do exist, they differ substantially and lack guidance in many key areas. Collaborative multidisciplinary work that provides guidance in these areas may lead to increased participation in physical activity and exercise and facilitate better patient outcomes.
Supporting information S1